在Haskell中按长度过滤列表项

Question

I have a list like ["a","ab","abc", "abcd"]

How to get a list that only has the items which have a length > 2.

Means the result is ["abc","abcd"].

Answer 1

Natalie's answer is perfectly correct, but as an alternate form you could also write it as

filter ((> 2) . length) ["a", "ab", "abc", "abcd"]

Or with list comprehension as

[str | str <- ["a", "ab", "abc", "abcd"], length str > 2]

All three are equivalent

Answer 2

filter (\x -> length x > 2) ["a","ab","abc", "abcd"]